Arkansas State University Department of Chemistry and Physics

CHEM4204 Homework 5

Lattice Energy and Born-Haber cycle

1) Calculate the Lattice energy (U) for CaO from the Born-Haber cycle: DH_f  = -635.5, DH_I.E. = 1735, DH_E.A. = 702, 1/2 DH_dis = 249.5, DH_vap = 192 kJ/mol.   Draw the Born-Haber cycle and label all parts.

2) Calculate the Lattice energy (U) for CaO a) using a CsCl lattice and b) using the rock salt lattice.  Ca-O distance, 183 pm.  Compare the two and tell which the favored lattice is.

Due Monday, March 11, 2019.  (15 points)